Democrats said the upswing is due to several factors, including opposition to Republican President Donald Trump and support for #RedForEd, the movement to increase teacher pay and funding for Arizona schools.

Steven Slugocki, Maricopa County Democratic Party chairman, said those sentiments, combined with a flood of new candidates in contested primary fights, drew first-time voters.

“If there’s one good thing that came from this presidency, it’s that there are people getting involved in the process for the first time ever," he said.

There are still more GOP voters in the state, but Democrats narrowed the statewide gap in voter turnout between the parties to 12 percent — its lowest level since 1994.

Republicans cast about 56 percent of ballots in the primary, compared with 44 percent for Democrats.

Can Democrats sustain momentum?

While Democrats have narrowed the gap, Republicans have a strong voter-registration edge in Arizona: 1.26 million voters are Republicans; 1.22 million are independents; 1.11 million are Democrats.

Republicans contend a strong economy and federal tax reforms that cut costs for many small businesses could boost the party's fortunes for the Nov. 6 general election.

GOP strategist Constantin Querard said the surge in Democratic turnout can be attributed to the fact the party had far more contested primaries than past election cycles.

"There's no reason to just show up and rubber-stamp the one choice you have in a race," he said. "It's not a surprise they're breaking records (now)."

Querard said while Trump might have motivated more liberal activists to run for office, turnout in the primary grew because of other factors, principally having more candidates on the ballot.

However, Democratic political consultant Lisa Fernandez said the upswing in turnout isn't an aberration.

She said Democrats have worked to register new Arizona voters for at least a decade. Those efforts have come to fruition, she said, at the same time concerns about Trump are at the forefront of voters' minds.

Plus, Fernandez said, voters are energized by the diverse, large slate of Democratic candidates talking about issues that directly affect them, such as education funding.

"They understand that if they want education funded, if they want real change, they need to elect Democrats," she said.